Semiconductor device and manufacturing method thereof

ABSTRACT

A separation layer containing a halogen element is formed over a glass substrate by a plasma CVD method; a semiconductor element is formed over the separation layer; and separation is then performed inside the separation layer or at its interface, so that the large-area glass substrate and the semiconductor element are detached from each other. In order to perform detachment at the interface between the glass substrate and the separation layer, the separation layer may have concentration gradient of the halogen element, and the halogen element is contained more near the interface between the separation layer and the glass substrate than in the other areas.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor device having a circuitwhich includes a thin film transistor (hereinafter referred to as aTFT), and also relates to a manufacturing method thereof. For example,the present invention relates to an electronic appliance in which anelectro-optic device typified by a liquid crystal display panel or alight-emitting display device including an organic light-emittingelement is provided as a component.

It is to be noted that the semiconductor device in this specificationrefers to all devices that can function by utilizing semiconductorcharacteristics, and electro-optic devices, semiconductor circuits, andelectronic appliances are all semiconductor devices.

2. Description of the Related Art

In recent years, a technique for manufacturing a thin film transistor(TFT) by using a semiconductor thin film (with a thickness of from aboutseveral to several hundred nanometers) formed over a substrate having aninsulating surface has attracted attention. Thin film transistors arewidely applied to electronic devices such as ICs and electro-opticdevices, and urgent development is expected on thin film transistors asswitching elements of image display devices in particular.

Among a variety of applications of such image display devices, whichhave been devised, application to portable appliances has particularlyattracted attention. Glass substrates and quartz substrates are oftenused; however, they have disadvantages in that they are easily brokenand they are heavy. Therefore, it has been tried to form TFT elementsover a substrate which has flexibility, typically a plastic film whichis flexible.

Consequently, a technique has been suggested in which an element formedover a glass substrate is separated from the substrate and transferredto another base material such as a plastic film.

The present applicant has suggested a separation and transfer techniquein Patent Document 1. Patent Document 1 describes a technique in which ametal layer (Ti, Al, Ta, W, Mo, Cu, Cr, Nd, Fe, Ni, Co, Ru, Rh, Pd, Os,or Ir) is formed over a substrate and an oxide layer is stackedthereover. In this technique, when the oxide layer is formed, a metaloxide layer of the metal layer is formed at an interface between themetal layer and the oxide layer, and separation is carried out in alater step by utilizing this metal oxide layer.

Patent Document 1: Japanese Published Patent Application No. 2003-174153

SUMMARY OF THE INVENTION

The present invention discloses a technique in which an elementmanufactured through a relatively-low-temperature (lower than 600° C.)process, which is typified by a TFT formed using an amorphous siliconfilm or the like, a TFT formed using an organic semiconductor film, alight-emitting element, or a passive element (such as a sensor, anantenna, a resistor, or a capacitor), is detached (i.e., separated) froma glass substrate and disposed (i.e., transferred) to a flexiblesubstrate (typically a plastic film).

A TFT formed using an amorphous silicon film or the like or a TFT formedusing an organic semiconductor film can be directly formed over aplastic film; however, since plastic films are soft, it is necessary toprepare a manufacturing equipment exclusively for plastic films. Whenmass production is carried out, the manufacturing equipment suppliesplastic films in accordance with a roll-to-roll method.

Furthermore, when a TFT is formed using an amorphous semiconductor film,an organic semiconductor film, or the like directly over a plastic film,there is a risk that the plastic film will be exposed to a solvent oretching gas that is used in a TFT manufacturing process, resulting inthat the quality of the plastic film itself will change. In addition,when a TFT is formed using zinc oxide directly over a plastic film, ifthe plastic film is irradiated with plasma that is generated in asputtering method or the like, the plastic film itself will becomedeformed. Moreover, there is another risk that moisture or the like willbe absorbed into or released from the plastic film in the TFTmanufacturing process, resulting in that an element will becontaminated. Additionally, because plastic films have lower heatresistance and higher degree of heat-induced expansion and contractionas compared to glass substrates, it is difficult to carefully controlthe process temperature of each step of the manufacturing process.

In the case of employing the separation method described in PatentDocument 1, at least two layers need to be formed because an oxide layeris formed after a metal layer is formed over a glass substrate with theuse of a sputtering apparatus. Moreover, when the metal layer containsan impurity, there is a risk that the impurity will diffuse into asemiconductor layer which is formed later.

In the case of using a sputtering apparatus for forming the metal layer,a member called a target is used. Although depending on the kind, thepurity, and the size of metal, a target is expensive. In particular, alarge-sized target corresponding to a large-area glass substrate isexpensive. In addition, a target needs to be changed periodically. It isalso an object of the present invention to reduce the manufacturing costof a device which is formed by a separation method.

A separation layer containing a halogen element is formed over alarge-area glass substrate by a plasma CVD method; a semiconductorelement is formed over the separation layer; and then the large-areaglass substrate and the semiconductor element are detached from eachother by performing separation inside the separation layer or at aninterface of the separation layer. It is to be noted that the upperlimit of temperatures during the manufacturing process for thesemiconductor element is lower than a temperature at which the halogenelement in the separation layer is desorbed. As the halogen element,fluorine or chlorine can be used. Fluorine and chlorine are desorbedfrom the separation layer at temperatures of about 600° C. or higher

A semiconductor layer formed by a plasma CVD method is used as theseparation layer. As the semiconductor layer, typically, an amorphoussilicon film, which is an amorphous semiconductor film, is used. In acase of forming a semiconductor layer containing a halogen element byusing a plasma CVD method, the halogen element can be contained at aconstant concentration without depending on a substrate temperature atthe time of formation of the semiconductor layer. On the other hand, ina case of forming a semiconductor layer containing hydrogen by using aplasma CVD method, the concentration of hydrogen differs depending on asubstrate temperature. Thus, with the halogen element which can becontained at a constant concentration, separation can be performed withhigh yield.

In order to perform detachment at the interface between the glasssubstrate and the separation layer, the separation layer may haveconcentration gradient of fluorine. The halogen element can be containedmore near the interface between the glass substrate and the separationlayer than in the other areas. For example, the halogen element can becontained near the interface between the glass substrate and theseparation layer when the amorphous silicon film is formed after afilm-formation chamber of a plasma CVD apparatus has an atmospherecontaining the halogen element. In this case, the concentration of thehalogen element has its peak near the interface between the glasssubstrate and the separation layer, and the concentration of the halogenelement decreases as the separation layer is formed. That is to say, itis not particularly necessary that the separation layer contain thehalogen element at a uniform concentration. As long as the halogenelement can be contained at least near the interface between the glasssubstrate and the separation layer, detachment can be performed in alater step with the interface functioning as a cleavage plane.

The concentration of the halogen element in the separation layer isequal to or higher than 1×10¹⁷ cm⁻³ and equal to or lower than 2×10²⁰cm⁻³. The separation is difficult to perform when the concentration ofthe halogen element is lower than 1×10¹⁷ cm⁻³. On the other hand,concentrations higher than 2×10²⁰ cM⁻³ have a risk of causing peeling ina later step.

In addition to the halogen element, the separation layer may containanother element such as hydrogen, carbon, oxygen, or nitrogen. Theconcentration of each element is preferably in the range that peelingdoes not occur in a later step.

The separation layer has a thickness more than or equal to 10 nm andless than 500 nm. In the case where the amorphous silicon film is formedafter the film-formation chamber of the plasma CVD apparatus has theatmosphere containing the halogen element, when the film thicknessexceeds 100 nm, the amorphous silicon film may include a regioncontaining the halogen element and a region excluding the halogenelement (a region including the halogen element less than the lowerlimit of detection by secondary ion mass spectrometry (hereinafterreferred to as SIMS)).

With the provision of a single layer of the semiconductor layercontaining the halogen element over the glass substrate, thesemiconductor element provided over the semiconductor layer can bedetached from the glass substrate. The present invention can simplifythe manufacturing process.

A first buffer layer may be provided between the semiconductor elementand the separation layer in order to relieve the stress of thesemiconductor layer containing the halogen element. An insulating layersuch as a silicon oxide film or a silicon nitride film is used as thefirst buffer layer. In a case of forming the first buffer layer by aplasma CVD method, an amorphous silicon film containing fluorine and asilicon oxide film over the amorphous silicon film can be formed by thesame plasma CVD apparatus without exposure to the air. When the sameplasma CVD apparatus is used, impurity mixture and the like at the timeof delivery between different film-formation apparatuses can beprevented.

By using a gas, such as nitrogen trifluoride, for cleaning thefilm-formation chamber, the film-formation chamber of the plasma CVDapparatus has the atmosphere containing the halogen element, so thatcleaning of the film-formation chamber for maintenance and the formationof the separation layer can be performed in the same step. Therefore,time of cleaning separately can be saved. Moreover, the separation layercan be formed just after the cleaning.

In the case of performing detachment at an interface between theseparation layer and the first buffer layer, the halogen element can becontained more near the interface between the separation layer and thefirst buffer layer than in the other areas. When the detachment isperformed at the interface between the glass substrate and theseparation layer, a step of removing the separation layer is performedin some cases. However, the step of removing the separation layer is notnecessary when the detachment is performed at the interface between theseparation layer and the first buffer layer.

An aspect of the present invention disclosed in this specification is amethod of manufacturing a semiconductor device, which includes thefollowing steps: forming a semiconductor layer containing a halogenelement over a substrate having an insulating surface; forming a firstbuffer layer over the semiconductor layer; forming a semiconductorelement or a light-emitting element over the first buffer layer; andperforming detachment at an interface between the substrate and thesemiconductor layer, inside the semiconductor layer, or at an interfacebetween the semiconductor layer and the first buffer layer.

In the above structure, when the semiconductor layer is formed so thatthe concentration of the halogen element near the interface between thesemiconductor layer and the substrate is higher than that near theinterface between the semiconductor layer and the first buffer layer,the detachment can be performed at the interface between the substrateand the semiconductor layer. For example, when the semiconductor layeris formed after generating plasma by using nitrogen trifluoride, theconcentration of the halogen element near the interface between thesemiconductor layer and the substrate can be made higher than that nearthe semiconductor layer and the first buffer layer. Alternatively, theconcentration of the halogen element near the interface between thesemiconductor layer and the substrate may be made higher than that nearthe interface between the semiconductor layer and the first buffer layerby doping with the halogen element after the formation of thesemiconductor layer, in accordance with an ion implantation method or anion doping method.

The detachment is possible at the interface between the semiconductorlayer and the first buffer layer when the semiconductor layer is formedso that the concentration of the halogen element near the interfacebetween the semiconductor layer and the first buffer layer is higherthan that near the interface between the semiconductor layer and thesubstrate. For example, when fluorine plasma treatment is performedafter the formation of the semiconductor layer, the concentration of thehalogen element near the interface between the semiconductor layer andthe first buffer layer can be made higher than that near the interfacebetween the semiconductor layer and the substrate. Alternatively, theconcentration of the halogen element near the interface between thesemiconductor layer and the first buffer layer may be made higher thanthat near the interface between the semiconductor layer and thesubstrate by doping with the halogen element after the formation of thesemiconductor layer, in accordance with an ion implantation method or anion doping method.

The present invention achieves at least one of the above objects.

Moreover, a second buffer layer may be provided between the glasssubstrate and the separation layer. A silicon oxide film is used as thesecond buffer layer. The use of a silicon nitride film as the secondbuffer layer causes peeling. However, even when a silicon oxide film isused, peeling occurs if the composition ratio of the silicon oxide filmis Si=32%, 0=27%, N=24%, and H=17%. A silicon oxide film with acomposition ratio of Si=32%, 0=59%, N=7%, and H=2% can be used as thesecond buffer layer. A silicon oxide film containing nitrogen in itscomposition ratio is also called a silicon oxynitride film; however, inthis specification, even if nitrogen is contained in the compositionratio, a silicon oxide film containing more oxygen than nitrogen iscalled a silicon oxide film. Moreover, in this specification, even ifoxygen is contained in the composition ratio, a silicon nitride filmcontaining more nitrogen than oxygen is called a silicon nitride film.

This silicon oxide film (composition ratio: Si=32%, 0=59%, N=7%, andH=2%) was formed in 100 nm thick over a glass substrate, plasma wasgenerated by introducing nitrogen trifluoride into a chamber, and anamorphous silicon film was formed in 0.5 μm thick with fluorineremaining in the chamber. Just after the formation of the amorphoussilicon film, separation was performed by attaching a kapton tape. Fromthis tape separation experiment, separation of the amorphous siliconfilm has been confirmed as shown in FIG. 17A. That is to say, separationis possible without heat treatment. FIG. 17A is a photograph which showsa separation area 1702 where separation has been performed by attachinga tape 1703 so that a part of the amorphous silicon film formed over thesubstrate 1701 is separated. FIG. 17B is a pattern diagram thereof.

FIG. 15 shows SIMS measurement results of the sample before theseparation in the aforementioned tape separation experiment. FIG. 16shows SIMS measurement results of the sample after the separation.

According to the present invention, after elements such as TFTs areformed by using an existing manufacturing equipment for large-area glasssubstrates, the elements can be transferred to a flexible substratetypified by a plastic substrate. Therefore, the facility cost can bereduced drastically.

After the semiconductor element is detached from the glass substrate,the separation layer may be removed. Alternatively, the separation layermay remain so that the semiconductor layer containing fluorine canfunction as a blocking layer.

Another aspect of the present invention is a semiconductor device whichincludes a semiconductor layer containing a halogen element over aplastic substrate; and a semiconductor element or a light-emittingelement over the semiconductor layer containing the halogen element,where the concentration of the halogen element in the semiconductorlayer is equal to or higher than 1×10¹⁷ cm⁻³ and equal to or lower than2×10¹⁹)cm⁻³.

In the above structure, the halogen element is fluorine or chlorine.With the above structure, the semiconductor layer containing fluorine orchlorine can prevent impurity intrusion from outside even after theplastic substrate and the semiconductor element are attached to eachother after the separation. Since a glass substrate contains alkalimetal, in a case of using a TFT as the semiconductor element, there is arisk that alkali metal diffusing from the glass substrate degradesoperating characteristics or reliability of the TFT. Accordingly, thesemiconductor layer containing fluorine or chlorine is effective in thatthe semiconductor layer can function as a blocking layer for blockingdiffusion of alkali metal to the semiconductor element in steps beforethe separation.

Moreover, in the above structure, an adhesive layer is provided betweenthe plastic substrate and the semiconductor layer containing the halogenelement.

Further, a buffer layer may be provided between the semiconductorelement or the light-emitting element, and the semiconductor layercontaining the halogen element.

The present invention can be used regardless of an element structure ofthe semiconductor element, such as a TFT structure. For example, atop-gate TFT, a bottom-gate (inverted-staggered) TFT, or a staggered TFTcan be used. The TFT is not limited to a single-gate transistor, and maybe a multi-gate transistor having a plurality of channel formationregions, such as a double-gate transistor.

According to the present invention, a large-sized display device using aflexible substrate can be manufactured. In addition, a passive matrixliquid crystal display device and a passive matrix light-emittingdevice, and moreover an active matrix liquid crystal display device andan active matrix light-emitting device can be manufactured.

Additionally, the flexible substrate refers to a plastic substrate thatis formed as a film, for example, a plastic substrate made frompolyethylene terephthalate (PET), polyethersulfone (PES), polyethylenenaphthalate (PEN), polycarbonate (PC), nylon, polyetheretherketone(PEEK), polysulfone (PSF), polyetherimide (PEI), polyarylate (PAR),polybutylene terephthalate (PBT), or the like.

Even when the substrate has a large area, the separation layer withreduced manufacturing cost can be provided by forming the amorphoussilicon film containing fluorine with the use of a parallel plate plasmaCVD apparatus (hereinafter referred to as a PCVD apparatus).

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1E are cross-sectional views showing manufacturing steps ofa liquid crystal display device (Embodiment Mode 1).

FIGS. 2A to 2D are cross-sectional views showing manufacturing steps ofa light-emitting device (Embodiment Mode 2).

FIGS. 3A and 3B each show an example of a cross-sectional structure ofan organic TFT (Embodiment Mode 2).

FIG. 4 is a schematic view of a capacitively-coupled plasma CVDapparatus.

FIG. 5A is a top view and FIGS. 5B and 5C are cross-sectional views,each showing a passive matrix light-emitting device (Embodiment Mode 3).

FIG. 6 is a perspective view of a passive matrix light-emitting device(Embodiment Mode 3).

FIG. 7 is a top view of a passive matrix light-emitting device(Embodiment Mode 3).

FIGS. 8A and 8B are top views each showing a passive matrixlight-emitting device (Embodiment Mode 3).

FIG. 9 is a cross-sectional view of a passive matrix light-emittingdevice (Embodiment Mode 3).

FIGS. 10A to 10D are cross-sectional views showing manufacturing stepsof an antenna, and FIG. 10E is a perspective view showing amanufacturing step of a semiconductor device.

FIGS. 11A to 11D are top views each showing a semiconductor devicefunctioning as a wireless chip.

FIG. 12A is a block diagram showing a semiconductor device of thepresent invention, and FIG. 12B shows an example of an electronicappliance.

FIGS. 13A to 13G each show an example of a semiconductor device.

FIGS. 14A to 14C each show an example of an electronic appliance.

FIG. 15 shows SIMS measurement results before separation.

FIG. 16 shows SIMS measurement results after separation.

FIG. 17A is a photograph of a thin film after tape separation, and FIG.17B is a pattern diagram thereof.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, embodiment modes and embodiments of the present inventionwill be described with reference to the drawings. However, the presentinvention can be implemented in many different modes, and it is easilyunderstood by those skilled in the art that various changes andmodifications can be made without any departure from the spirit andscope of the present invention. Accordingly, the present invention isnot construed as being limited to the described content of theembodiment modes and embodiments included herein.

Embodiment Mode 1

An example of manufacturing a liquid crystal display device will beexplained here with reference to FIGS. 1A to 1E and FIG. 4.

First, an amorphous silicon film 102 containing fluorine is formed overa substrate 101. A glass substrate is used as the substrate 101. Theamorphous silicon film 102 containing fluorine is formed by a PCVDmethod to a thickness greater than or equal to 10 nm and less than 500nm. The amorphous silicon film 102 containing fluorine may be formed byusing a material gas containing fluorine (CF₄, CHF₃, C₂F₆, or SF₆).Here, the amorphous silicon film 102 is formed in such a way that acapacitively-coupled plasma CVD apparatus is used and etching isperformed inside a process chamber with the use of a fluorine-based gas(for example, flow rate of nitrogen trifluoride: 100 SCCM, flow rate ofargon: 50 SCCM, RF output: 300 W at 27 MHz, pressure in the processchamber: 13 Pa, and substrate temperature: 250° C.), i.e., chambercleaning is performed, and then the amorphous silicon film 102 isdeposited by an autodoping method utilizing fluorine remaining in theprocess chamber. Here, the amorphous silicon film 102 containingfluorine is formed under the condition where the flow rate of monosilanegas is 100 SCCM, the RF output is 20 W at 27 MHz, the pressure in theprocess chamber is 33 Pa, the substrate temperature is 250° C., and thefilm thickness is about 50 nm.

Instead of fluorine, another halogen element may be used. For example,Cl₂, CCl₄, BCl₃, ClF₃, or the like may be used as the material gas.

FIG. 14 is a schematic view of a capacitively-coupled plasma CVDapparatus. A capacitively-coupled plasma CVD apparatus 1000 shown inFIG. 4 is provided with a process chamber 1012 including a substrateelectrode plate 1002, a high-frequency electrode plate 1004, a gasintroducing portion 1006, and an exhaust port 1008. The substrateelectrode plate 1002 and the high-frequency electrode plate 1004 aredisposed in parallel to each other. The substrate electrode plate 1002is at a ground potential, whereas the high-frequency electrode plate1004 is at a potential different from the ground potential. An object tobe processed (corresponding to the substrate 101 in FIG. 4) is held bythe substrate electrode plate 1002. The electric discharge of thecapacitively-coupled plasma CVD apparatus 1000 is carried out by an ACpower source 1010, so that plasma is generated between the substrateelectrode plate 1002 and the high-frequency electrode plate 1004.

The amorphous silicon film 102 containing fluorine thus obtainedcontains fluorine at a concentration equal to or higher than 1×10¹⁷ cm³and equal to or lower than 2×10²⁰ cm³, hydrogen at a concentration equalto or higher than 1×10²¹ cm⁻³ and equal to or lower than 1×10²² cm⁻³,carbon at a concentration equal to or higher than 1×10¹⁵ cm⁻³ and equalto or lower than 2×10¹⁸ cm⁻³, nitrogen at a concentration equal to orhigher than 1×10¹⁸ cm⁻³ and equal to or lower than 1×10²⁰ cm⁻³ andoxygen at a concentration equal to or higher than 1×10¹⁵ cm⁻³ and equalto or lower than 1×10¹⁹ cm⁻³.

Although the amorphous silicon film 102 containing fluorine is formedover the glass substrate in this example, a buffer layer may be formedbetween the glass substrate and the amorphous silicon film 102containing fluorine. A silicon oxide film may be used as the bufferlayer.

The amorphous silicon film 102 containing fluorine which is formed nearthe periphery of the substrate may be removed as selected so thatseparation will not occur from an edge of the substrate in a later stepof delivery or the like. In this case, separation will not occur in alater separation step at the periphery of the substrate where theamorphous silicon film containing fluorine, which will serve as aseparation layer, has been removed as selected. Therefore, a trigger ofseparation is preferably formed by laser light or a cutter, so thatseparation is performed from a place where the trigger is formed.

Next, a first insulating film 103 serving as an etching stopper film isformed over the amorphous silicon film 102 containing fluorine. In orderto remove the amorphous silicon film 102 containing fluorine in a laterstep, an insulating film such as a silicon oxide film or a siliconnitride film is used as the first insulating film 103. As the firstinsulating film 103, a film obtained by applying and baking a solutioncontaining polysilazane or siloxane polymer, a photocurable organicresin film, a thermosetting organic resin film, or the like may be used.

Subsequently, a first conductive film is formed over the firstinsulating film 103, and then a mask is formed over the first conductivefilm. The first conductive film is formed of an element selected fromTa, W, Ti, Al, Cu, Cr, Nd, or the like or an alloy or compound materialcontaining any of these elements as its main component, as a singlelayer or stacked layers. The first conductive film is formed by asputtering method, an evaporation method, a CVD method, a coatingmethod, or the like, as appropriate. Next, the first conductive film isetched by using the mask, thereby forming a gate electrode 104.

Subsequently, a second insulating film 105 serving as a gate insulatingfilm is formed over the gate electrode 104. As the second insulatingfilm 105, an insulating film such as a silicon oxide film, a siliconnitride film, or a silicon oxynitride film is used. Alternatively, afilm obtained by applying and baking a solution containing polysilazaneor siloxane polymer, a photocurable organic resin film, a thermosettingorganic resin film, or the like may be used as the second insulatingfilm 105.

Next, a semiconductor film 106 with an amorphous structure is formedover the second insulating film 105. The semiconductor film 106 with anamorphous structure is formed using a microcrystalline semiconductorfilm or an amorphous semiconductor film manufactured by a thermal CVDmethod, a sputtering method, or a vapor deposition method by using asemiconductor material gas typified by silane or germane. Thisembodiment mode shows an example in which an amorphous silicon film isused as the semiconductor film. As the semiconductor film,alternatively, zinc oxide or an oxide of zinc-gallium-indium which ismanufactured by a sputtering method or a PLD (pulse laser deposition)method may be used. In this case, a gate insulating film is preferablyformed of an oxide including aluminum or titanium.

Subsequently, as a semiconductor film containing an impurity elementimparting one conductivity, an amorphous semiconductor film 107containing an impurity element imparting n-type conductivity is formedto a thickness of from 20 to 80 nm. The amorphous semiconductor film 107containing an impurity element imparting n-type conductivity is formedover the entire surface by a known method such as a plasma CVD method ora sputtering method. A cross-sectional process diagram of what isobtained after processes up to this stage have been completed is shownin FIG. 1B.

Next, patterning is performed in accordance with a knownphotolithography technique, thereby forming an island-shapedsemiconductor layer and a semiconductor layer having conductivity.Instead of a known photolithography technique, a mask may be formed by adroplet discharging method or a printing method (such as reliefprinting, planography, intaglio printing, or screen printing) andetching may be performed as selected.

Next, a composition including a conductive material (such as silver,gold, copper, tungsten, or aluminum) is discharged as selected by adroplet discharging method, thereby forming a source electrode 112 and adrain electrode 113. Instead of a droplet discharging method, the sourceelectrode 112 and the drain electrode 113 may be formed in such a waythat a metal film (Ta, W, Ti, Al, Cu, Cr, Nd, or the like) is formed bya sputtering method, and the metal film is patterned by a knownphotolithography technique.

Next, semiconductor layers 110 and 111 having conductivity are formed byusing the source electrode 112 and the drain electrode 113 as masks. Thesemiconductor layers 110 and 111 are etched using the source electrode112 and the drain electrode 113 as masks so as to partially expose thesemiconductor film 106, and moreover, an upper part of the semiconductorfilm 106 is removed to form a semiconductor layer 109. The exposed partof the semiconductor layer 109 functions as a channel formation regionof a TFT.

Subsequently, a protection film 114 is formed to prevent the channelformation region of the semiconductor layer 109 from impuritycontamination. The protection film 114 is formed of a materialcontaining silicon nitride or silicon nitride oxide as a main component,by a sputtering method or a PCVD method. In this embodiment mode,hydrogenation treatment is performed after the protection film isformed. Thus, a TFT 108 is manufactured.

Next, an interlayer insulating film 115 is formed over the protectionfilm 114. The interlayer insulating film 115 is formed of a resinmaterial such as an epoxy resin, an acrylic resin, a phenolic resin, anovolac resin, a melamine resin, or a urethane resin. An organicmaterial such as benzocyclobutene, parylene, or polyimide which has alight-transmitting property; a compound material formed bypolymerization, such as a siloxane-based polymer; a composition materialcontaining a water-soluble homopolymer and a water-soluble copolymer; orthe like can also be used. Alternatively, an insulating film such as asilicon oxide film, a silicon nitride film, or a silicon oxynitride filmcan be used as the interlayer insulating film 115, and the insulatingfilm and the resin material may be stacked.

Next, patterning is performed in accordance with a knownphotolithography technique to remove the protection film 114 and theinterlayer insulating film 115 as selected, thereby forming a contacthole that reaches the drain electrode 113.

Then, a composition including a conductive material (such as silver,gold, copper, tungsten, or aluminum) is discharged as selected by adroplet discharging method, thereby forming first electrodes 116 whichare electrically connected to the drain electrode 113. In addition,second electrodes 117 are formed by a droplet discharging method inorder that an electric field in a direction parallel to the substratesurface can be formed between the first electrode 116 and the secondelectrode 117. It is to be noted that the first electrodes 116 and thesecond electrodes 117 are preferably disposed at an equal distance fromeach other, and a top surface of the electrodes may have a comb-likeshape.

Next, an orientation film 118 is formed so as to cover the firstelectrodes 116 and the second electrodes 117. A cross-sectional processdiagram of what is obtained after processes up to this stage have beencompleted is shown in FIG. 1C.

Then, a liquid crystal material, here polymer-dispersed liquid crystals,is used to fix a flexible substrate 121 so as to be opposite to thesubstrate 101. Polymer-dispersed liquid crystals are divided into twotypes depending on the dispersion state of the liquid crystals andpolymer materials. One of these two types is that in which droplets ofliquid crystals are dispersed in a polymer material and the liquidcrystals are discontinuous (called PDLC). The other is that in which apolymer material forms a network in liquid crystals and the liquidcrystals are continuous (called PNLC). Note that although either typemay be used in this embodiment mode, PDLC is used here. In thisembodiment mode, a polymer material 119 including liquid crystals 120fixes the flexible substrate 121. If necessary, a sealant may beprovided so as to surround the polymer material 119. Further, ifnecessary, a spacer (such as a bead spacer, a column spacer, or fiber)may be used to control the thickness of the polymer material 119.

Next, the TFT 108 and the flexible substrate 121 are separated from thesubstrate 101. Although detachment is performed at an interface betweenthe substrate 101 and the amorphous silicon film 102 containingfluorine, as shown in FIG. 1D, a place at which the detachment isperformed is not limited in particular as long as the TFT is not broken.The detachment may be performed inside the amorphous silicon film 102containing fluorine, or at an interface between the first insulatingfilm 103 and the amorphous silicon film 102 containing fluorine.

Next, the amorphous silicon film 102 containing fluorine is removed. Dryetching or wet etching is performed by using the first insulating film103 as an etching stopper. Since this embodiment mode explains anexample of manufacturing a transmissive liquid crystal display device,the amorphous silicon film 102 containing fluorine which decreases lighttransmittance is removed; however, in a case of manufacturing areflective liquid crystal display device, the amorphous silicon film 102containing fluorine may remain in the reflective liquid crystal displaydevice.

Moreover, although this embodiment mode shows the example in which muchfluorine is contained near the interface between the substrate and theamorphous silicon film containing fluorine, detachment can be performedat the interface between the first insulating film 103 and the amorphoussilicon film containing fluorine when much fluorine is contained nearthe interface between the first insulating film 103 and the amorphoussilicon film containing fluorine. In the latter case, a step of removingthe amorphous silicon film containing fluorine is unnecessary.

Next, a flexible substrate 123 is fixed to a surface of the firstinsulating film 103 by using an adhesive layer 122, in order to increasemechanical strength of the liquid crystal display device, as shown inFIG. 1E. In order to keep the space between the substrates withoutdepending on change in temperature, the flexible substrate 121 and theflexible substrate 123 are preferably formed of materials with the samecoefficient of thermal expansion. When the liquid crystal display devicehas enough mechanical strength, the flexible substrate 123 is notparticularly necessary.

In accordance with the above steps, an active matrix liquid crystaldisplay device using an amorphous silicon TFT can be manufactured. Theconductive layer formed by a droplet discharging method has lowadhesion; however, when the separation method of the present inventionwhich uses the amorphous silicon film 102 containing fluorine isemployed, separation is possible even though a part of wiring is formedusing a conductive layer formed by a droplet discharging method.

An electrophoretic display may be manufactured by using electronic inkinstead of polymer-dispersed liquid crystals. In this case, after thefirst electrodes 116 and the second electrodes 117 are formed,electronic ink may be applied by a printing method and then baked, andmay subsequently be fixed by the flexible substrate 121. Then, afterseparating the substrate, another flexible substrate may be used forsealing.

Embodiment Mode 2

Here, an example of manufacturing an active matrix light-emitting deviceusing an organic TFT will be explained with reference to FIGS. 2A to 2D.

First, a first silicon oxide film 202 (composition ratio: Si=32%, 0=59%,N=7%, H=2%) is formed in 115 nm thick over a substrate 201 by a plasmaCVD method with the use of SiH₄ and N₂O as a material gas.

Next, plasma is generated by using nitrogen trifluoride. Then, anamorphous silicon film is formed by a plasma CVD method with the use ofthe film-formation chamber with fluorine remaining therein. Thus, anamorphous silicon film 203 having a concentration peak of fluorine nearthe first silicon oxide film 202 is obtained.

Subsequently, a second silicon oxide film 204 is formed over theamorphous silicon film 203 to a thickness of from 10 to 200 nm(preferably 50 to 100 nm) by a plasma CVD method with the use of SiH₄,NH₃, and N₂O as a material gas. Here, the second silicon oxide film 204(composition ratio: Si=32%, 0=27%, N=24%, H=17%) is formed to athickness of 50 nm. A cross-sectional process diagram of what isobtained after processes up to this stage have been completed is shownin FIG. 2A.

Next, a conductive layer serving as a gate electrode is formed over thesecond silicon oxide film 204. The conductive layer may be formed of anymaterial as long as it is a metal which comes to have an insulatingproperty by nitridation and/or oxidation. The material is preferablytantalum, niobium, aluminum, copper, or titanium in particular. As analternative to those metals, tungsten, chromium, nickel, cobalt,magnesium, or the like is given. A method of forming the conductivelayer is not particularly limited, and the conductive layer may beformed by a sputtering method, an evaporation method, or the like andmay subsequently be processed into a desired shape by a method ofetching or the like. Alternatively, the conductive layer may be formedby an inkjet method or the like with the use of droplets that contain aconductor.

Next, a gate insulating film 212 including a nitride, an oxide, or anoxynitride of the aforementioned metal is formed by nitriding and/oroxidizing the conductive layer. It is to be noted that a part of theconductive layer other than the gate insulating film 212, which has beeninsulated, functions as a gate electrode 211.

Subsequently, a semiconductor layer 213 covering the gate insulatingfilm 212 is formed. For an organic semiconductor material used to formthe semiconductor layer 213, either a low-molecular material or amacromolecular material can be used, as long as it is an organicmaterial which has carrier transportability and which can change incarrier density by an electric field effect. There is no particularlimitation on the type of material used, and polycyclic aromaticcompounds, conjugated double bond compounds, metal phthalocyaninecomplexes, charge-transfer complexes, condensed ring tetracarboxylicacid diimides, oligothiophenes, fullerenes, carbon nanotubes, and thelike can be given. For example, polypyrrole, polythiophene,poly(3-alkylthiophene), polyphenylenevinylene,poly(p-phenylenevinylene), polyaniline, polydiacetylene, polyazulene,polypyrene, polycarbazole, polyselenophene, polyfuran,poly(p-phenylene), polyindole, polypyridazine, naphthacene, hexacene,heptacene, pyrene, chrysene, perylene, coronene, terrylene, ovalene,quaterrylene, circumanthracene, triphenodioxazine, triphenodithiazine,hexacene-6,15-quinone, polyvinyl carbazole, polyphenylene sulfide,polyvinylene sulfide, polyvinylpyridine, naphthalene tetracarboxylicacid diimide, anthracene tetracarboxylic acid diimide, C60, C70, C76,C78, and C84 and derivatives of any of these can be used. Furthermore,as specific examples of these materials, tetracene, pentacene,sexithiophene (6T), copper phthalocyanine,bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole), rubrene,poly(2,5-thienylene vinylene) (PTV), poly(3-hexylthiophene-2,5-diyl)(P3HT), and poly(9,9′-dioctyl-fluorene-co-bithiophene) (FST2), which aregenerally considered to be p-type semiconductors; and7,7,8,8-tetracyanoquinodimethane (TCNQ),3,4,9,10-perylenetetracarboxylic dianhydride (PTCDA),1,4,5,8-naphthalenetetracarboxylic dianhydride (NTCDA),N,N′-dioctyl-3,4,9,10-perylenetetracarboxylic diimide (PTCDI-C8H),copper hexadecafluorophthalocyanine (F₁₆CuPc);N,N′-bis(2,2,3,3,4,4,5,5,6,6,7,7,8,8,8-pentadecafluorooctyl)-1,4,5,8-naphthalenetetracarboxylic diimide (NTCDI-C8F),3′,4′-dibutyl-5,5″-bis(dicyanomethylene)-5,5″-dihydro-2,2′:5′,2″-terthiophene)(DCMI, and methanofullerene[6,6]-phenyl-C₆₁ butyric acid methyl ester(PCBM), which are generally considered to be n-type semiconductors; andthe like can be given. It is to be noted that the attributes of p-typeand n-type of organic semiconductors are not inherent to thesemiconductors. Although semiconductor materials have a tendency tobecome p-type or n-type depending on the relationship between thematerial and an electrode from which carriers are injected or on thestrength of the electric field when carriers are injected, thesemiconductor materials can be used as either p-type or n-type. It is tobe noted that, in the present embodiment mode, using p-typesemiconductors is more preferable.

These organic semiconductor materials can be used to form films by anevaporation method, a spin coating method, a droplet discharging method,or the like.

Next, buffer layers 214 are formed over the semiconductor layer 213 inorder to improve adhesiveness and chemical stability of an interface.For the buffer layers 214, an organic material that has conductivity (anorganic compound that exhibits electron acceptability, for example,7,7,8,8-tetracyanoquinodimethane (TCNQ);2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane (F₄-TCNQ); or thelike) or a composite material of an organic compound and a metal oxidemay be used. It is to be noted that the buffer layers 214 may be omittedif unnecessary.

Next, conductive layers 215 serving as a source electrode and a drainelectrode are formed over the buffer layers 214. There is no particularlimitation on a material used for the conductive layers 215; however, ametal such as gold, platinum, aluminum, tungsten, titanium, copper,tantalum, niobium, chromium, nickel, cobalt, or magnesium, or an alloythat contains any of these metals can be used. Alternatively, for othermaterials that can be used for the conductive layers 215, a conductivemacromolecular compound such as polyaniline, polypyrrole, polythiophene,polyacetylene, polydiacetylene, and the like can be given. It is to benoted that there is no limitation on the formation method of theconductive layers 215 as long as it is a method by which thesemiconductor layer 213 is not degraded, and the conductive layers 215may be manufactured by being processed into a desired shape by a methodof etching or the like after film formation by a sputtering method, anevaporation method, or the like. Furthermore, the conductive layers 215may be formed by an inkjet method or the like using droplets thatcontain a conductor. Through the above process, an organic transistor227 can be manufactured.

In addition, an organic insulating material of polyimide, polyamic acid,polyvinyl phenyl, or the like may be formed in contact with a lowersurface of the semiconductor layer 213. By this kind of structure,orientation of the organic semiconductor material can be improvedfurther, and the adhesiveness between the gate insulating film 212 andthe semiconductor layer 213 can be improved further.

Next, a method of manufacturing a light-emitting device that uses theorganic transistor 227 will be described.

Next, an interlayer insulating film 228 is formed to cover the organictransistor 227. Then, the interlayer insulating film 228 is etched asselected, thereby forming a contact hole that reaches one of theconductive layers 215. Next, a first electrode 210 that is electricallyconnected to the one of the conductive layers 215 is formed.Subsequently, a partition wall 221 is formed to cover edges of the firstelectrode 210. The partition wall 221 is formed of an insulatingmaterial and fulfills a function of insulating between a plurality ofthe first electrodes 210 that is arranged adjacent to each other.

Next, a light-emitting layer 222 is formed over a region of the firstelectrode 210 that does not come into contact with the partition wall221. The light-emitting layer 222 is formed of, in many cases, a singlelayer or stacked layers of an organic compound or a single layer orstacked layers of an inorganic compound. This specification alsoincludes a structure in which an inorganic compound is used in a part ofa film formed of an organic compound. For each of the layers in alight-emitting element, there is no limitation on a method of stackinglayers. As long as layers can be stacked, any kind of techniqueincluding a vacuum vapor deposition method, a spin coating method, aninkjet method, a dip coating method, or the like may be selected.

Next, a second electrode 223 is formed over the light-emitting layer222. A light-emitting element is formed at a place where the firstelectrode 210, the second electrode 223, and the light-emitting layer222 overlap with each other. It is to be noted that this light-emittingelement has an anode, a cathode, and a layer that contains an organiccompound or a layer that contains an inorganic compound, with whichluminescence (electroluminescence) generated by application of anelectric field is obtained (this type of layer will hereinafter bereferred to as an EL layer). In particular, an inorganic EL elementusing an inorganic thin film of ZnS:Mn and an organic EL element usingan organic evaporation thin film are bright, exhibit highly efficient ELlight emission, and are suitable for application in a display. It is tobe noted that there is no particular limitation on the structure of thelight-emitting element.

In this embodiment mode, the first electrode 210 is formed of a metalmaterial that reflects light, such as aluminum, silver, or an alloyincluding any of them, and the second electrode 223 is formed using atransparent conductive film.

Next, a protection film 224 is formed over the second electrode 223. Theprotection film 224 is an insulating film having a light-transmittingproperty. It is to be noted that the protection film 224 may be omittedif unnecessary.

Next, a flexible substrate 225 is fixed over the protection film 224with an adhesive layer 226 interposed therebetween. A sealant may beplaced so as to surround the adhesive layer 226 in order to strengthensealing. A cross-sectional process diagram of what is obtained afterprocesses up to this stage have been completed is shown in FIG. 2B.

Subsequently, detachment is performed at an interface between the firstsilicon oxide film 202 and the amorphous silicon film 203 or inside theamorphous silicon film 203, so that the organic transistor 227 and theflexible substrate 225 are separated from the substrate 201. FIG. 2Cshows that the detachment is performed at the interface between thefirst silicon oxide film 202 and the amorphous silicon film 203.

Next, in order to increase the mechanical strength of the light-emittingdevice, a flexible substrate 206 is fixed to a surface on which theseparation has been performed, i.e., the amorphous silicon film 203,with the use of an adhesive layer 205, as shown in FIG. 2D. If thelight-emitting device has enough mechanical strength, the flexiblesubstrate 206 is not particularly necessary.

Through the steps given above, an active matrix light-emitting devicethat uses an organic transistor can be manufactured. Since thisembodiment mode shows the example of the light-emitting device in whichemitted light passes through the flexible substrate 225, the amorphoussilicon film 203 remains in the light-emitting device.

The first electrode 210 may be formed using a transparent conductivefilm and the second electrode 223 may be formed of a metal material thatreflects light, such as aluminum, silver, or an alloy including any ofthem. In this case, the amorphous silicon film 203 is preferably removedafter the separation step.

Instead of the structure shown in FIG. 2C, the organic transistor mayhave a structure shown in FIG. 3A or 3B.

FIG. 3A illustrates a structure called a bottom-contact structure. It isto be noted that portions that are the same as those in FIGS. 2A to 2Dare denoted by the same reference numerals. In the case of using thebottom-contact structure, a step of photolithography or the like can becarried out easily for microfabrication of a source wiring and a drainwiring. For this reason, the structure of the organic transistor may beselected as appropriate based on its advantages and disadvantages.

The first silicon oxide film 202, the amorphous silicon film 203, andthe second silicon oxide film 204 are stacked over the substrate 201. Agate electrode 331 is formed over the second silicon oxide film 204.There is no particular limitation on a material used to form the gateelectrode 331. For example, a metal such as gold, platinum, aluminum,tungsten, titanium, copper, molybdenum, tantalum, niobium, chromium,nickel, cobalt, or magnesium; an alloy that contains any of thesemetals; a conductive macromolecular compound such as polyaniline,polypyrrole, polythiophene, polyacetylene, or polydiacetylene;polysilicon that is doped with an impurity; and the like can be given.It is to be noted that there is no particular limitation on theformation method of the gate electrode 331, and the gate electrode 331may be manufactured by being processed into a desired shape by a methodof etching or the like after film formation by a sputtering method, anevaporation method, or the like. Furthermore, the gate electrode 331 maybe formed by an inkjet method or the like by using droplets that containa conductor.

Next, an insulating film 332 that covers the gate electrode 331 isformed. The insulating film 332 is formed using an inorganic insulatingmaterial such as silicon oxide, silicon nitride, or silicon oxynitride.It is to be noted that the insulating film 332 of any of these materialscan be formed by a coating method such as a dipping method, a spincoating method, or a droplet discharging method; a CVD method; asputtering method; or the like. This insulating film 332 may besubjected to nitridation and/or oxidation by using high-density plasma.By high-density plasma nitridation, a silicon nitride film that containsnitrogen at a higher concentration can be obtained. The high-densityplasma is generated by use of high-frequency microwaves, for example,microwaves with a frequency of 2.45 GHz. By use of this kind ofhigh-density plasma, oxygen (or a gas that contains oxygen), nitrogen(or a gas that contains nitrogen), or the like can be activated byplasma excitation, and these are made to react with the insulating film.In high-density plasma that has the characteristic of having a lowelectron temperature, since the kinetic energy of an active species islow, a film can be formed with less plasma damage and fewer defectscompared to a film formed by conventional plasma treatment. In addition,with use of high-density plasma, because the surface of the insulatingfilm 332 can be made less rough, carrier mobility can be increased.Furthermore, the orientation of organic semiconductor materials used toform the semiconductor layer over the insulating film 332, whichfunctions as a gate insulating film, becomes easy to align.

Next, a source electrode 314 and a drain electrode 315 are formed overthe insulating film 332. Then, a semiconductor layer 313 is formedbetween the source electrode 314 and the drain electrode 315. For thesemiconductor layer 313, the same materials as that used to form thesemiconductor layer 213 shown in FIG. 2B described above can be used.After forming the organic transistor with such a structure, separationis performed and the organic transistor is transferred to the flexiblesubstrate.

Furthermore, a structure of FIG. 3B will be described. The structure ofFIG. 3B is a structure that is referred to as a top-gate structure. Itis to be noted that portions that are the same as those in FIGS. 2A to2D are denoted by the same reference numerals.

The first silicon oxide film 202, the amorphous silicon film 203, andthe second silicon oxide film 204 are stacked over the substrate 201. Asource electrode 414 and a drain electrode 415 are formed over thesecond silicon oxide film 204. Next, a semiconductor layer 413 is formedbetween the source electrode 414 and the drain electrode 415. Then, aninsulating film 442 is formed to cover the semiconductor layer 413, thesource electrode 414, and the drain electrode 415. Next, a gateelectrode 441 is formed over the insulating film 442. The gate electrode441 overlaps with the semiconductor layer 413 with the insulating film442 interposed therebetween. After forming the organic transistor withsuch a structure, separation is performed and the organic transistor istransferred to the flexible substrate.

In this manner, even with these kinds of structures of organictransistors, separation can be performed and the organic transistors canbe transferred to a flexible substrate by the present invention.

Instead of the organic transistor, a transistor with its semiconductorlayer including an oxide of zinc-gallium-indium or zinc oxide which ismanufactured by a sputtering method or a PLD method can also be used. Inthis case, the structure of FIG. 3A or 3B can be applied. When thesemiconductor layer includes zinc oxide or an oxide ofzinc-gallium-indium, the gate insulating film is preferably formed of anoxide including aluminum or titanium. In this manner, the presentinvention is effective even when a transistor is formed through aprocess in which the substrate is irradiated with plasma. After thetransistor is formed over a plasma-resistant substrate, the transistorcan be separated and transferred to the flexible substrate.

This embodiment mode can be freely combined with Embodiment Mode 1. Forexample, a liquid crystal display device can be manufactured by usingthe organic transistor shown in Embodiment Mode 2 instead of theamorphous TFT shown in Embodiment Mode 1. Moreover, a light-emittingdevice can be manufactured by using the amorphous TFT shown inEmbodiment Mode 1 instead of the organic transistor shown in EmbodimentMode 2.

Embodiment Mode 3

Here, an example of manufacturing a passive matrix light-emitting deviceby using a flexible substrate will be explained with reference to FIGS.5A to 9.

A passive matrix (simple matrix) light-emitting device has a structurein which a plurality of anodes is provided in parallel stripe form (bandform) and a plurality of cathodes is provided in parallel stripe form sothat the anodes and the cathodes are perpendicular to each other and inwhich a light-emitting layer or a fluorescent layer is inserted at anintersection of the anode and the cathode. Consequently, a pixel locatedat an intersection of a selected (voltage-applied) anode and a selectedcathode comes to be lit up.

FIG. 5A is a diagram illustrating a top view of a pixel portion beforesealing. FIG. 5B is a cross-sectional view taken along a chain line A-Ain FIG. 5A, and FIG. 5C is a cross-sectional view taken along a chainline B-B′ in FIG. 5A.

Over a first substrate 501, as in Embodiment Mode 2, a first siliconoxide film 502, an amorphous silicon film 503 containing fluorine, and asecond silicon oxide film 504 are stacked. Over the second silicon oxidefilm 504, a plurality of first electrodes 513 is arranged in stripe format an equal distance to each other. Furthermore, over the firstelectrodes 513, a partition wall 514 that has openings, with eachopening corresponding to a pixel, is provided, and the partition wall514 that has openings is formed of an insulating material (aphotosensitive or non-photosensitive organic material (polyimide,acrylic, polyamide, polyimide-amide, or benzocyclobutane) or an SOG film(for example, an SiO_(x) film that has an alkyl group)). It is to benoted that each opening corresponding to a pixel serves as alight-emitting region 521.

Over the partition wall 514 that has openings, a plurality ofmutually-parallel reversely-tapered partition walls 522 is provided tointersect with the first electrodes 513. The reversely-tapered partitionwalls 522 are formed by a photolithography method in such a way that apositive photosensitive resin of which unexposed part is left remainingas a pattern is used and the amount of exposure to light and length oftime for image development are adjusted so that the lower part of thepattern is etched more than the other parts.

FIG. 6 is a perspective view illustrating the device right after theplurality of parallel reversely-tapered partition walls 522 is formed.The same portions as those in FIGS. 5A to 5C are denoted by the samereference numerals.

The height of the reversely-tapered partition walls 522 is set to begreater than the combined film thicknesses of a conductive film and astacked-layer film that, includes a light-emitting layer. Astacked-layer film that includes a light-emitting layer, and aconductive film are formed and stacked with respect to the firstsubstrate having the structure shown in FIG. 6. Then, the films areisolated into a plurality of electrically independent regions as shownin FIGS. 5A to 5C, and stacked-layer films 515R, 515G, and 515B thateach include a light-emitting layer, and second electrodes 516 areformed. The second electrodes 516 are electrodes of mutually-parallelstripe form, which extend in a direction intersecting with the firstelectrodes 513. It is to be noted that the stacked-layer film includinga light-emitting layer and a conductive film are also formed over thereversely-tapered partition walls 522; however, they are isolated fromthe stacked-layer films 515R, 515G, and 515B that each include alight-emitting layer, and the second electrodes 516.

Here, an example of forming a light-emitting device is shown. Thelight-emitting device shown here is capable of full-color display whereemission of three different colors of light (R, C, and B) is obtained byselective formation of the stacked-layer films 515R, 515G, and 515B thateach includes a light-emitting layer. The stacked-layer films 515R,515G, and 515B that each includes a light-emitting layer are formed intoa mutually-parallel stripe pattern.

Furthermore, light-emitting elements of a single color may be providedby formation of stacked-layer films including light-emitting layerswhich emit light of the same emission color over the entire surface, andthe light-emitting device may be set to be one capable of monochromedisplay or one capable of area color display. In addition, alight-emitting display device capable of full-color display may beobtained by a combination of a color filter and a light-emitting devicecapable of white light emission.

Next, a top view of a light-emitting module in which an FPC and the likeare provided is shown in FIG. 7.

It is to be noted that “light-emitting device” in the presentspecification refers to an image display device, a light-emittingdevice, or a light source (which includes a lighting device). Moreover,a module in which a connector, for example, a flexible printed circuit(FPC), a tape automated bonding tape (TAB tape), or a tape carrierpackage (TCP) is attached to a light-emitting device; a module in whichan edge of a TAB tape or a TCP is attached to a printed circuit board;and a module in which an integrated circuit (IC) is directly mounted ona light-emitting device by a chip on glass (COG) method are allconsidered to be included in the term “light-emitting device.”

In a pixel portion performing image display as shown in FIG. 7, scanninglines and data lines are arranged to intersect with each other so thatthe scanning lines and data lines are mutually orthogonal.

The first electrode 513, the second electrode 516, and thereversely-tapered partition wall 522 of FIGS. 5A to 5C correspond to ascanning line 603, a data line 602, and a partition wall 604 of FIG. 7,respectively. A light-emitting layer is interposed between the data line602 and the scanning line 603, and an intersection indicated by a region605 is defined as a single pixel.

It is to be noted that the scanning line 603 is electrically connectedto a connecting wiring 608 at an edge of the wiring, and the connectingwiring 608 is connected to an FPC 609 b via an input terminal 607. Inaddition, the data line 602 is connected to an FPC 609 a via an inputterminal 606.

Next, a first flexible substrate is fixed using a first adhesive layer.

Next, the light-emitting element is separated from the first substrate601. Subsequently, in order to seal the light-emitting device morefirmly, a second flexible substrate is fixed to a surface where theseparation has been performed, with the use of a second adhesive layer.

In addition, if needed, optical films such as a polarizer, a circularpolarizer (including an elliptical polarizer), a retarder plate (aquarter-wave plate, a half-wave plate), or a color filter may beprovided on an emission surface, as appropriate. Moreover, the polarizeror circular polarizer may be provided with an antireflective film. Forexample, antiglare treatment can be performed by which reflected lightis diffused on unevenness of a surface so as to reduce glare.

Through the above steps, a flexible passive matrix light-emitting devicecan be manufactured. Because thermocompression bonding is performed tomount an FPC, it is preferable that mounting of the FPC bythermocompression bonding be performed on a hard substrate. Inaccordance with the present invention, separation can be performed aftermounting the FPC and the elements can be transferred to the flexiblesubstrate.

The example in which the driver circuit is not provided over thesubstrate has been explained with reference to FIG. 7. An example of amethod of manufacturing a light-emitting module in which an IC chiphaving a driver circuit is provided will hereinafter be described withreference to FIGS. 8A and 8B.

First, over a first substrate 701, as in Embodiment Mode 2, a firstsilicon oxide film, an amorphous silicon film containing fluorine, and asecond silicon oxide film are formed, Over this second silicon oxidefilm, a data line 702 (which also functions as an anode) is formed. Thedata line 702 has a stacked-layer structure where the lower layer is areflective metal film and the upper layer is a transparent conductiveoxide film. Simultaneously, connecting wirings 708, 709 a, and 709 b andinput terminals are formed.

Next, a partition wall that has openings, with each openingcorresponding to a pixel 705, is provided. Then, over the partition wallthat has openings, a plurality of mutually-parallel reversely-taperedpartition walls 704 is formed to intersect with the data lines 702. Atop-view diagram of what is obtained after the steps outlined above havebeen completed is shown in FIG. 8A.

Subsequently, a stacked-layer film that includes a light-emitting layerand a transparent conductive film are formed and stacked, and then theyare isolated into a plurality of electrically independent regions asshown in FIG. 8B. Thus, the stacked-layer film including alight-emitting layer and scanning lines 703 including a transparentconductive film are formed. The scanning lines 703 formed using atransparent conductive film are electrodes of mutually-parallel stripeform that extend in a direction of intersection with the data lines 702.

Next, in a region at the periphery (outer side) of a pixel portion, anIC 706 on the data line side and an IC 707 on the scanning line side,each of which has a driver circuit that is used to transmit a variety ofsignals to the pixel portion, are mounted by a COG method. TCP or a wirebonding method may be used as a mounting technique, instead of the COGmethod. TCP is a method in which an IC is mounted on a TAB tape and theTAB tape is connected to a wiring over an element formation substrate,so that an IC is mounted. The IC 706 on the data line side and the IC707 on the scanning line side may be ICs formed using a siliconsubstrate, or they may have driver circuits formed using TFTs over aglass substrate, a quartz substrate, or a plastic substrate. Inaddition, an example is shown in which one IC is provided on one side;however, a plurality of ICs, divided into individual parts, may beprovided on one side.

It is to be noted that each of the scanning lines 703 is electricallyconnected to one of the connecting wirings 708 at the edge of thewiring, and each of the connecting wirings 708 is connected to the IC707 on the scanning line side. This is because forming the IC 707 on thescanning line side over the reversely-tapered partition walls 704 isdifficult.

The IC 706 on the data line side, which is provided to have thestructure described above, is connected to an FPC 711 via the connectingwiring 709 a and an input terminal 710. Furthermore, the IC 707 on thescanning line side is connected to an FPC via the connecting wiring 709b and an input terminal.

Moreover, integration is achieved by mounting an IC chip 712 (a memorychip, a CPU chip, a power supply circuit chip, or the like).

Next, a first flexible substrate is fixed using a first adhesive layerso as to cover the pixel portion.

Next, the light-emitting element is separated from the first substrate701. Subsequently, in order to seal the light-emitting device morefirmly, a second flexible substrate is fixed onto a surface where theseparation has been performed, with the use of a second adhesive layer.

FIG. 9 shows an example of a cross-sectional structure taken along achain line C-D of FIG. 8B after fixing the second flexible substrate.

An amorphous silicon film 802 containing fluorine and a second siliconoxide film 811 are provided over a second flexible substrate 810 withthe use of a second adhesive layer 819. A lower layer 812 is areflective metal film and an upper layer 813 is a transparent conductiveoxide film. The upper layer 813 is preferably formed using a conductivefilm that has a high work function; as well as a film that containsindium tin oxide, for example, a film that contains a transparentconductive material such as indium tin oxide containing silicon orindium zinc oxide (IZO) in which zinc oxide is mixed into indium oxide,or a compound of a combination of any of these materials can be used. Inaddition, the lower layer 812 is formed using a silver film, an aluminumfilm, or an aluminum-alloy film.

A partition wall 814 for insulating adjacent data lines from each otheris formed of resin, and regions surrounded by the partition wall allhave the same area corresponding to light-emitting regions.

A scanning line 816 (cathode) is formed so as to intersect with a dataline (anode). The scanning line 816 (cathode) is formed using atransparent conductive film such as a film of indium tin oxide, indiumtin oxide containing silicon, or indium zinc oxide (IZO) in which zincoxide is mixed into indium oxide. Because the light-emitting device ofthe present embodiment mode is an example of a top-emissionlight-emitting device in which emitted light passes through a firstflexible substrate 820, it is important that the scanning line 816 istransparent.

Furthermore, the first flexible substrate 820 is attached to seal apixel portion in which each of a plurality of light-emitting elements isarranged at a point of intersection of a scanning line and a data linethat sandwich a stacked-layer film 815 having a light-emitting layer,and the pixel portion is filled with a first adhesive layer 817. For thefirst adhesive layer 817, a UV curable resin, a thermosetting resin, asilicone resin, an epoxy resin, an acrylic resin, a polyimide resin, aphenolic resin, polyvinyl chloride (PVC), polyvinyl butyral (PVB), orethylene vinyl acetate (EVA) can be used.

A terminal electrode is formed at an edge of the second flexiblesubstrate 810. At this edge, an FPC (flexible printed circuit board) 832that is connected to an external circuit is attached. The terminalelectrode is formed using stacked layers of a reflective metal film 830,a transparent conductive oxide film 829, and a conductive oxide filmthat extends from the second electrode; however, there is no particularlimitation on the structure of the terminal electrode.

As the method for mounting the FPC 832, a connection method that uses ananisotropic conductive material or a metal bump or a wire bonding methodcan be employed. In FIG. 9, the connection is performed using ananisotropic conductive adhesive 831.

In addition, an IC chip 823 provided with a driver circuit that is usedto transmit a variety of signals to the pixel portion is electricallyconnected to the periphery of the pixel portion by anisotropicconductive materials 824 and 825. Moreover, in order to form a pixelportion corresponding to color display of XGA class, 3072 data lines and768 scanning lines are necessary. The data lines and scanning linesformed at these numbers are sectioned for every several blocks at anedge of the pixel portion, thereby forming lead wirings. The leadwirings are collected in accordance with the pitch of output terminalsof the IC.

Through the above steps, a light-emitting module with the IC chipmounted, the IC chip being sealed by the second flexible substrate 810and the first flexible substrate 820, can be manufactured. Becausethermocompression bonding is performed to mount the IC chip, it ispreferable that mounting of the IC by thermocompression bonding beperformed on a hard substrate. In accordance with the present invention,separation can be performed after mounting the IC chip and the elementscan be transferred to the flexible substrate.

Although this embodiment mode shows the example of the light-emittingdevice which has the amorphous silicon film 802 containing fluorine,there is no particular limitation and the amorphous silicon film 802containing fluorine may be removed after the separation. Moreover, whenthe amorphous silicon film 802 containing fluorine is formed so as tohave a concentration peak of fluorine near the interface between theamorphous silicon film 802 and the second silicon oxide film 811, whichis formed later, detachment can be performed at the interface betweenthe amorphous silicon film 802 and the second silicon oxide film 811.

This embodiment mode can be freely combined with the other EmbodimentModes.

Embodiment Mode 4

This embodiment mode will show an example of manufacturing asemiconductor device functioning as a wireless chip. The semiconductordevice shown in the present embodiment mode is a device by which readingand writing of data can be carried out without contact. Datatransmission types are roughly divided into three types: anelectromagnetic coupling method in which a pair of coils is arrangedopposite to each other and data is communicated by mutual induction, anelectromagnetic induction method in which data is communicated by aninduction electromagnetic field, and an electric wave method in whichdata is communicated using electric waves. Any of these methods may beused.

Furthermore, there are two ways for providing an antenna used for thedata transmission. One way is to provide an antenna over an elementsubstrate where a plurality of elements and a memory element areprovided. The other way is to provide a terminal portion over an elementsubstrate where a plurality of elements and a memory element areprovided, and an antenna provided to a separate substrate is connectedto the terminal portion.

A manufacturing method in the case where an antenna provided to aseparate substrate is connected to a terminal portion of an elementsubstrate will hereinafter be presented in this embodiment mode.

First, as in Embodiment Mode 1, an amorphous silicon film 902 containingfluorine is formed over a heat-resistant substrate 901 so that there isa concentration peak of fluorine toward a surface of the amorphoussilicon film 902 containing fluorine, A cross-sectional process diagramof the substrate after processes up to this stage have been completed isshown in FIG. 10A. As the heat-resistant substrate 901, a substrate inwhich an inorganic component and an organic component are combined at amolecular level is used. As well as a substrate having alight-transmitting property, a substrate which resists bakingtemperatures (about 300° C.) of a conductive layer formed by a coatingmethod and which does not change in shape largely may be used as theheat-resistant substrate. Alternatively, a semiconductor substrate, aglass substrate, a quartz substrate, or a ceramic substrate can be usedas the heat-resistant substrate. However, a plastic substrate which haslow heat resistance against heat treatment at 300° C. for 30 minutes isnot suitable for the heat-resistant substrate 901 because it may bend.

Subsequently, a conductive layer 904 functioning as an antenna is formedover the amorphous silicon film 902 containing fluorine, as shown inFIG. 10B. The conductive layer 904 functioning as an antenna is formedby discharging droplets or paste containing a conductor such as gold,silver, or copper by a droplet discharging method (such as an inkjetmethod or a dispensing method) and drying and baking the droplets orpaste. By the formation of the conductive layer 904 by a dropletdischarging method, the number of steps can be reduced, which leads costreduction. Alternatively, the conductive layer 904 may be formed by ascreen printing method. In the case of using a screen printing method,as a material of the conductive layer 904 functioning as an antenna, aconductive paste in which conductive particles, each with a diameter offrom several nanometers to several tens of micrometers, are dissolved inor dispersed throughout an organic resin is printed as selected. For theconductive particles, metal particles of one or more of silver, gold,copper, nickel, platinum, palladium, tantalum, molybdenum, or titanium;microparticles of a silver halide; or dispersive nanoparticles can beused. Moreover, for the organic resin that is contained in theconductive paste, one or more organic resins selected from organicresins that function as binders, solvents, dispersants, or coatingmaterials of metal particles can be used. Typically, organic resins suchas an epoxy resin and a silicone resin can be given. Furthermore, in theformation of the conductive layer 904, it is preferable that theconductive paste be baked after being extruded. Alternatively,microparticles containing solder or lead-free solder as the maincomponent may be used, and in this case, it is preferable that fineparticles with a diameter of 20 μm or less be used. Solder and lead-freesolder both have an advantage in that they are inexpensive. Instead ofthe materials given above, ceramic, ferrite, or the like may be appliedfor the antenna.

In the case where the antenna is manufactured using a screen printingmethod or a droplet discharging method, after formation of the antennainto a desired shape, baking is performed. The baking is performed attemperatures ranging from 200° C. to 300° C. The baking is possible evenat temperatures lower than 200° C.; however, when the baking temperatureis lower than 200° C., there is a risk that the conductivity of theantenna cannot be maintained or that even the communication distance forthe antenna will become short. In consideration of these points, it ispreferable that, after the antenna is formed over a separate substrate,namely, a heat-resistant substrate, the antenna be separated from thesubstrate and transferred to an element substrate. When a memory elementusing an organic material is employed as a memory element provided tothe element substrate, there is a risk that the memory element changesin quality depending on the baking temperature of the antenna, whichaffects data writing and the like. Even in this point, it isadvantageous that the antenna provided to a separate substrate isconnected to the terminal portion of the element substrate.

Moreover, the antenna may be formed by gravure printing or the likeinstead of being formed by a screen printing method, or the antenna canbe formed of a conductive material by using a plating method or thelike. In some cases, an antenna formed by a plating method has lowadhesiveness depending on a plating material and a plating condition;therefore, it is effective to employ a separation method which uses anamorphous silicon film containing fluorine of the present invention.

Subsequently, a flexible substrate 906 is attached using a resin layer905 in order to protect the conductive layer 904, as shown in FIG. 10C.

Next, separation is performed as shown in FIG. 10D, so that theconductive layer 904, the resin layer 905, and the flexible substrate906 can be detached from the heat-resistant substrate 901 and theamorphous silicon film 902 containing fluorine. It is to be noted thatthe detachment is performed at an interface between the amorphoussilicon film containing fluorine and the conductive layer 904, i.e., aninterface of the amorphous silicon film near which much fluorine iscontained. As long as the flexible substrate 906 has sufficientadhesiveness with respect to the conductive layer 904 by the resin layer905, separation can be performed by pulling the flexible substrate 906after fixing the resin layer 905. The yield increases because theseparation can be performed by the addition of only relatively weakforce in the separation method using the amorphous silicon filmcontaining fluorine of the present invention. Since the separation canbe performed by the addition of only relatively weak force in theseparation method using the amorphous silicon film containing fluorineof the present invention, change in shape of the flexible substrate 906occurring while separation is performed can be suppressed, and theamount of damage that the conductive layer 904 receives can be reduced.Moreover, in the separation method using the amorphous silicon filmcontaining fluorine of the present invention, the conductive layer 904can be exposed; therefore, in a case of connection with another element,electrical connection with another element is easy.

Next, by compression bonding using an anisotropic conductive material, aterminal portion of the element substrate and the conductive layer 904are electrically connected to each other. As shown in FIG. 10E, anelement substrate 907 is disposed in contact with a surface on which theconductive layer 904 is formed.

Although FIG. 10E shows the example of the element substrate 907 whichhas a smaller area than the flexible substrate 906, there is noparticular limitation, and the element substrate 907 may have almost thesame area as the flexible substrate 906 or may have a larger area thanthe flexible substrate 906.

Finally, another flexible substrate is attached so as to cover theantenna and the element substrate 907, thereby completing asemiconductor device functioning as a wireless chip. When there is noneed, another flexible substrate does not have to be attached.

Here, as a method of transmitting signals in the semiconductor device,an electromagnetic coupling method or an electromagnetic inductionmethod (for example, 13.56 MHz band) is applied. Because electromagneticinduction by change in magnetic field density is used, the upper surfaceof the conductive layer that functions as an antenna is formed into aring shape (for example, as a loop antenna) or a spiral shape (forexample, as a spiral antenna) in FIG. 10; however, there is noparticular limitation on the shape into which the conductive layer isformed.

Alternatively, as a method of transmitting signals in the semiconductordevice, a microwave (for example, UHF band (from 860 MHz to 960 MHz),2.45 GHz band, or the like) method can be applied. In this case, theshape such as the length of the conductive layer that functions as anantenna may be set as appropriate in consideration of the wavelength ofthe electromagnetic waves used in the transmission of signals. Examplesof a conductive layer 912 functioning as an antenna and a chip-formsemiconductor device 913 having an integrated circuit, which are formedover a flexible substrate 911, are shown in FIGS. 11A to 11D. Forexample, an upper surface of the conductive layer that functions as anantenna can be formed into a linear shape (for example, as a dipoleantenna (see FIG. 11A)), a planar shape (for example, as a patch antenna(see FIG. 11B)), a ribbon shape (see FIGS. 11C and 11D), or the like. Inaddition, the shape of the conductive layer that functions as an antennais not limited to being a linear shape but the conductive layer may beformed into a curved-line shape or a meandering shape or into a shapethat is a combination of any of these shapes, in consideration of thewavelengths of the electromagnetic waves.

Furthermore, a structure of the semiconductor device obtained throughthe above steps will be described with reference to FIG. 12A. As shownin FIG. 12A, a semiconductor device 1120 obtained by the presentinvention has a function of communicating data without contact and has apower supply circuit 1111, a clock generator circuit 1112, a datademodulation or modulation circuit 1113, a controller circuit 1114 thatis used to control another circuit, an interface circuit 1115, a memorycircuit 1116, a data bus 1117, an antenna 1118, a sensor 1121, and asensor circuit 1122.

The power supply circuit 1111 is a circuit that generates a variety ofpower sources supplied to internal circuits of the semiconductor device1120 based on alternating current signals input from the antenna 1118.The clock generator circuit 1112 is a circuit that generates a varietyof clock signals that are supplied to internal circuits of thesemiconductor device 1120 based on alternating current signals inputfrom the antenna 1118. The data demodulation or modulation circuit 1113has a function of demodulating or modulating data communicated with areader/writer 1119. The controller circuit 1114 has a function ofcontrolling the memory circuit 1116. The antenna 1118 has a function oftransmitting and receiving electric waves. The reader/writer 1119communicates with and controls the semiconductor device and controls theprocessing of data thereof. It is to be noted that the semiconductordevice is not limited to having the above structure; for example, thestructure may be one that includes additional elements such as a powersupply voltage limiter circuit or hardware used exclusively forcryptography processing.

The memory circuit 1116 has a memory element in which an organiccompound layer or a phase-change layer is interposed between a pair ofconductive layers. It is to be noted that the memory circuit 1116 mayhave only a memory element in which an organic compound layer or aphase-change layer is interposed between a pair of conductive layers, orthe memory circuit 1116 may have a memory circuit that has anotherstructure. A memory circuit with another structure corresponds to one ormore selected from a DRAM circuit, an SRAM circuit, an FeRAM circuit, amask ROM circuit, a PROM circuit, an EPROM circuit, an EEPROM circuit,or a flash memory circuit.

The sensor 1121 is formed using a semiconductor element such as aresistor, a capacitive-coupling element, an inductive-coupling element,a photovoltaic element, a photoelectric conversion element, athermoelectromotive element, a transistor, a thermistor, a diode, or thelike. The sensor circuit 1122 detects changes in impedance, reactance,inductance, voltage, or current; converts signals from analog to digital(A/D conversion); and outputs the converted signals to the controllercircuit 1114.

Furthermore, the present embodiment mode can be freely combined withEmbodiment Mode 1 or Embodiment Mode 2. For example, the elementsubstrate which has an integrated circuit formed using the TFT obtainedby Embodiment Mode 1 or Embodiment Mode 2 and on which the separationhas been performed (flexible substrate) and the flexible substrateprovided with the antenna, which is obtained by this embodiment mode,can be attached to each other, so that the both substrates areelectrically connected to each other.

By the present invention, a semiconductor device that functions as achip that has a processor circuit (hereinafter also referred to as aprocessor chip, a wireless chip, a wireless processor, a wirelessmemory, and a wireless tag) can be formed. The application of asemiconductor device obtained by the separation method of the presentinvention covers a wide range; for example, the semiconductor device canbe provided and used in paper money, coins, securities, certificates,unregistered bonds, packaging containers, books, storage media, personalbelongings, vehicles, food products, clothing, healthcare products,livingware, medicines, electronic appliances, and the like.

Paper money and coins are money that circulates in the market andinclude what are used in the same way as currency within a limitedregion (cash vouchers), memorial coins, and the like. Securities referto checks, bonds, promissory notes, and the like, and a chip 90 that hasa processor circuit can be provided therein (see FIG. 13A). Certificatesrefer to driver's licenses, residence certificates, and the like, and achip 91 that has a processor circuit can be provided therein (see FIG.13B). Personal belongings refer to bags, glasses, and the like, and achip 97 that has a processor circuit can be provided therein (see FIG.13C). Unregistered bonds refer to stamps, rice coupons, various kinds ofgift vouchers, and the like. Packaging containers refer to wrappingpaper for box lunch and the like, plastic bottles, and the like, and achip 93 that has a processor circuit can be provided therein (see FIG.13D). Books refer to printed books and the like, and a chip 94 that hasa processor circuit can be provided therein (see FIG. 13E). Storagemedia refer to DVDs, video tapes, and the like, and a chip 95 that has aprocessor circuit can be provided therein (see FIG. 13F). Vehicles referto wheeled vehicles such as bicycles, ships, and the like, and a chip 96that has a processor circuit can be provided therein (see FIG. 13G).Food products refer to foods, beverages, and the like. Clothing refersto garments, footwear, and the like. Healthcare products refer tomedical equipment, healthcare equipment, and the like, Livingware refersto furniture, lighting equipment, and the like. Medicines refer topharmaceutical products, agrochemicals, and the like. Electronicappliances refer to liquid crystal display devices, EL display devices,television devices (television image receiver, flat-screen televisionimage receiver), cellular phones, and the like.

A semiconductor device obtained by the separation method of the presentinvention is fixed to an article by being mounted to a printed circuitboard, by being attached to a surface of the article, or by beingembedded in the article. For example, as for a book, the semiconductordevice is embedded in the paper; as for packaging made of an organicresin, the semiconductor device is embedded in the organic resin; thus,the semiconductor device is fixed to each article. The semiconductordevice of the present invention can achieve reduction in size,thickness, and weight; therefore, even after the semiconductor device isfixed to an article, the design quality of the article itself is notdegraded. In addition, by provision of the semiconductor device obtainedby the present invention in paper money, coins, securities, unregisteredbonds, certificates, and the like, an authentication function can beprovided; if this authentication function is utilized, forgery can beprevented. Furthermore, by provision of the semiconductor deviceobtained by the present invention in packaging containers, storagemedia, personal belongings, food products, clothing, livingware,electronic appliances, and the like, improvement in the efficiency ofsystems such as inspection systems can be realized.

Next, one mode of an electronic appliance in which a semiconductordevice obtained by the separation method of the present invention isprovided will be explained with reference to drawings. An example of anelectronic appliance illustrated here is of a cellular phone, whichincludes cases 2700 and 2706, a panel 2701, a housing 2702, a printedcircuit board 2703, operation buttons 2704, and a battery 2705 (see FIG.12B). The panel 2701 is detachably incorporated in the housing 2702, andthe housing 2702 is fitted to the printed circuit board 2703. The shapeand dimensions of the housing 2702 are changed as appropriate to conformto the shape and dimensions of the electronic appliance in which thepanel 2701 is incorporated. A plurality of packaged semiconductordevices is mounted on the printed circuit board 2703, and as one out ofthe plurality of semiconductor devices, a semiconductor device that isobtained by the present invention can be used. The plurality ofsemiconductor devices mounted on the printed circuit board 2703functions as any of the following: a controller, a central processingunit (CPU), memory, a power supply circuit, an audio processing circuit,a transmitter-receiver circuit, or the like.

The panel 2701 is connected to the printed circuit board 2703 through aconnection film 2708. The panel 2701, the housing 2702, and the printedcircuit board 2703 are placed inside the cases 2700 and 2706 togetherwith the operation buttons 2704 and the battery 2705. A pixel region2709 included in the panel 2701 is positioned in such a way that it isvisible through an open window provided in the case 2700.

As described above, because a flexible substrate is used, thesemiconductor device obtained by the separation method of the presentinvention has the characteristics of being thin and lightweight; by theaforementioned characteristics, limited space inside the cases 2700 and2706 of the electronic appliance can be used effectively.

Since the semiconductor device has a memory element with a simplestructure in which an organic compound layer is sandwiched between apair of conductive layers, an electronic appliance using an inexpensivesemiconductor device can be provided.

It is to be noted that the cases 2700 and 2706 are shown as an exampleof the shape of the appearance of a cellular phone, and electronicappliances of the present embodiment mode can be changed into variousmodes depending on the functions and intended use.

This embodiment mode can be freely combined with the other EmbodimentModes.

The present invention including the aforementioned structure will bedescribed in more detail in embodiments hereinafter shown.

Embodiment 1

A liquid crystal display device or a light-emitting device obtained bythe present invention can be employed in various modules (such as anactive matrix liquid crystal module, an active matrix EL module, or anactive matrix EC module). That is to say, the present invention can beimplemented in all the electronic appliances having these incorporatedin display portions.

As those kinds of electronic appliances, cameras such as video camerasand digital cameras, head mount displays (goggle-type displays), carnavigation systems, projectors, car stereos, personal computers,portable information terminals (mobile computers, cellular phones,electronic book readers, and the like), and the like can be given.Examples of these appliances are shown in FIGS. 14A to 14C.

FIGS. 14A and 14B each show a television device. As for display panels,there are a case in which only a pixel portion is formed in the displaypanel and a scanning line side driver circuit and a signal line sidedriver circuit are mounted to the display panel by a TAB method; a casein which only a pixel portion is formed in the display panel and ascanning line side driver circuit and a signal line side driver circuitare mounted to the display panel by a COG method; a case in which a TFTis formed, a pixel portion and a scanning line side driver circuit areformed over the same substrate, and a signal line side driver circuit isformed separately and mounted to the display panel as a driver IC; acase in which a pixel portion, a signal line side driver circuit, and ascanning line side driver circuit are formed over the same substrate;and the like, but any kind of mode may be used.

For structures of other external circuits, on a video signal input side,there are a video signal amplifier circuit used to amplify video signalsout of signals received by a tuner; a video signal processing circuitused to convert signals output from the video signal amplifier circuitinto color signals corresponding to each color of red, green, and blue;a control circuit used to convert those video signals in accordance withinput specifications for a driver IC; and the like. The control circuitoutputs signals to both the scanning line side and the signal line side.When digital driving is performed, a signal divider circuit may beprovided on the signal line side so that an input digital signal isdivided into a plurality of signals and supplied.

Among signals that are received by a tuner, audio signals aretransmitted to an audio signal amplifier circuit, and the output thereofis supplied to a speaker through an audio signal processing circuit. Acontroller circuit receives information of a receiving station(receiving frequency) and information about control of volume from aninput portion, and signals are sent out to the tuner or the audio signalprocessing circuit.

A television device can be completed by incorporation of a displaymodule into a chassis, as shown in each of FIGS. 14A and 14B. An objectincluding from a display panel to an FPC that is connected to thedisplay panel is also referred to as a display module. A main screen2003 is formed by the display module, and speaker portions 2009,operation switches, and the like are provided as accessory equipment. Asthus described, a television device can be completed.

As shown in FIG. 14A, a display panel 2002 using display elements isincorporated into a chassis 2001. As well as reception of generaltelevision broadcast, communication of information in one direction(from a transmitter to a receiver) or in two directions (between atransmitter and a receiver or between receivers) can be carried out withthe use of a receiver 2005 by connection to communication network via amodem 2004 with or without wires. Operations of the television devicecan be carried out using switches that are incorporated into the chassisor by a remote control device 2006 provided separately, and a displayportion 2007 that displays output information may be provided in theremote control device, as well.

Furthermore, the television device may have a structure in which asubscreen 2008 used to display channel, volume, and the like is formedusing a second display panel, in addition to the main screen 2003. Inthis structure, the main screen 2003 may be formed using an EL displaypanel that has an excellent viewing angle, and the subscreen may beformed using a liquid crystal display panel by which display at lowpower consumption is possible. In addition, in order to give priority toreduction of power consumption, the main screen 2003 may be formed usinga liquid crystal display panel and the subscreen may be formed using anEL display panel capable of being turned on or off.

FIG. 14B shows a television device that has a large display portion, forexample with a size of from 20 inches to 80 inches, and includes achassis 2010, a keyboard 2012 used for operations, a display portion2011, speaker portions 2013, and the like. The present invention isapplied to manufacture the display portion 2011. Since the displayportion of FIG. 14B uses a flexible substrate that can be curved, thetelevision device has a curved display portion. Because the shape of thedisplay portion can be designed thus freely, a television device thathas a desired shape can be manufactured.

By the present invention, display devices can be formed by a simpleprocess, which leads to cost reduction. Consequently, with a televisiondevice formed using the present invention, even a television device witha large-screen display portion can be formed at low cost.

Needless to say, the present invention is not limited to being used intelevision devices, and the present invention can be used in a varietyof applications such as monitors for personal computers, and moreoverdisplay media that have a large area such as information display boardsin railway stations, airports, and the like and advertisement displayboards on streets.

In addition, FIG. 14C shows a portable information terminal (electronicbook reader) and includes a main body 3001, display portions 3002 and3003, a storage medium 3004, operation switches 3005, an antenna 3006,and the like. The separation method of the present invention can beapplied to the display portions 3002 and 3003. By use of a flexiblesubstrate, the portable information terminal can be made morelightweight. The separation method of the present invention can be usedwhen an antenna is formed over a plane substrate and incorporatedinstead of the antenna shown in FIG. 14C.

The present embodiment can be freely combined with any one of EmbodimentMode 1 through Embodiment Mode 4.

Embodiment 2

This embodiment will show an example in which an electrophoretic displaydevice is used for the display portion described in Embodiment 1.Typically, the electrophoretic display device is applied to the displayportion 3002 or the display portion 3003 of the portable book reader(electronic book reader) that is shown in FIG. 14C.

The electrophoretic display device (electrophoretic display) is alsoreferred to as electronic paper and has advantages in that it has thesame level of readability as plain paper, it has less power consumptionthan other display devices, and it can be made thin and lightweight.

Electrophoretic displays can have various modes. Electrophoreticdisplays contain a plurality of microcapsules dispersed in a solvent ora solute, each microcapsule containing first particles having positivecharge and second particles having negative charge. By applying anelectric field to the microcapsules, the particles in the microcapsulesare moved in opposite directions to each other and only the color of theparticles concentrated on one side is exhibited. It is to be noted thatthe first particles and the second particles each contain pigment and donot move without an electric field. Moreover, the colors of the firstparticles and the second particles are set to be different from eachother (this includes particles that are colorless).

In this way, an electrophoretic display is a display that utilizes aso-called dielectrophoretic effect by which a substance that has a highdielectric constant move to a region in which there is a high electricfield. An electrophoretic display does not need to use a polarizer and acounter substrate, which are required in a liquid crystal displaydevice, and both the thickness and weight of the electrophoretic displaydevice can be a half of those of a liquid crystal display device.

A solution in which the aforementioned microcapsules are dispersedthroughout a solvent is referred to as electronic ink. This electronicink can be printed on a surface of glass, plastic, cloth, paper, or thelike. Furthermore, by use of a color filter or particles that have apigment, color display is possible, as well.

In addition, if a plurality of the aforementioned microcapsules isarranged as appropriate over a substrate so as to be interposed betweena pair of electrodes, a display device can be completed, and display canbe performed by application of an electric field to the microcapsules.For example, the active matrix substrate obtained by Embodiment Mode 1can be used. Although electronic ink can be printed directly on aplastic substrate, when the display device is of active matrix type, itis preferable that elements and electronic ink be formed over a glasssubstrate and then separated from the glass substrate and attached to aplastic substrate as a flexible substrate according to the separationmethod of Embodiment Mode 1 or Embodiment Mode 2, rather than thatelements are formed over a plastic substrate that is sensitive to heatand organic solvents. This is because the device can be manufacturedunder a wide range of conditions in a process.

It is to be noted that the first particles and the second particles inthe microcapsules may each be formed of a single material selected froma conductive material, an insulating material, a semiconductor material,a magnetic material, a liquid crystal material, a ferroelectricmaterial, an electroluminescent material, an electrochromic material, ora magnetophoretic material or formed of a composite material of any ofthese.

The present embodiment mode can be freely combined with any one ofEmbodiment Modes 1 through 4 and Embodiment 1.

According to the present invention, after elements such as TFTs areformed by using an existing manufacturing equipment for large-area glasssubstrates, the elements can be transferred to a flexible substrate.Therefore, facility cost can be drastically reduced.

This application is based on Japanese Patent Application serial no.2007-144360 filed with Japan Patent Office on May 31, 2007, the entirecontents of which are hereby incorporated by reference.

1. A method of manufacturing a semiconductor device, comprising: forminga semiconductor layer containing a halogen element over a substratehaving an insulating surface; forming a buffer layer over thesemiconductor layer; forming at least one of a semiconductor element anda light-emitting element over the buffer layer; and separating thebuffer layer and the at least one of the semiconductor element and thelight-emitting element from the substrate.
 2. The method ofmanufacturing a semiconductor device, according to claim 1, wherein thehalogen element is fluorine or chlorine.
 3. The method of manufacturinga semiconductor device, according to claim 1, wherein the semiconductorlayer is an amorphous silicon film formed by a plasma CVD method.
 4. Themethod of manufacturing a semiconductor device, according to claim 1,wherein the buffer layer is an insulating layer formed by a plasma CVDmethod.
 5. The method of manufacturing a semiconductor device, accordingto claim 1, wherein concentration of the halogen element contained inthe semiconductor layer is equal to or higher than 1×10¹⁷ cm⁻³ equal toor lower than 2×10² cm⁻³.
 6. The method of manufacturing a semiconductordevice, according to claim 1, wherein the substrate having an insulatingsurface is a glass substrate.
 7. A method of manufacturing asemiconductor device, comprising: forming a semiconductor layercontaining a halogen element over a substrate having an insulatingsurface; forming a buffer layer over the semiconductor layer; forming atleast one of a semiconductor element and a light-emitting element overthe buffer layer; and performing detachment at an interface between thesubstrate and the semiconductor layer.
 8. The method of manufacturing asemiconductor device, according to claim 7, wherein the halogen elementis fluorine or chlorine.
 9. The method of manufacturing a semiconductordevice, according to claim 7, wherein the semiconductor layer is anamorphous silicon film formed by a plasma CVD method.
 10. The method ofmanufacturing a semiconductor device, according to claim 7, wherein thebuffer layer is an insulating layer formed by a plasma CVD method. 11.The method of manufacturing a semiconductor device, according to claim7, wherein concentration of the halogen element in the semiconductorlayer near the interface between the semiconductor layer and thesubstrate is higher than concentration of the halogen element in thesemiconductor layer near the interface between the semiconductor layerand the buffer layer.
 12. The method of manufacturing a semiconductordevice, according to claim 7, wherein concentration of the halogenelement contained in the semiconductor layer is equal to or higher than1×10¹⁷ cm⁻³ equal to or lower than 2×10²⁰ cm⁻³.
 13. The method ofmanufacturing a semiconductor device, according to claim 7, wherein thesubstrate having an insulating surface is a glass substrate.
 14. Amethod of manufacturing a semiconductor device, comprising: forming asemiconductor layer containing a halogen element over a substrate havingan insulating surface; forming a buffer layer over the semiconductorlayer; forming at least one of a semiconductor element and alight-emitting element over the buffer layer; and performing detachmentat an interface between the semiconductor layer and the buffer layer.15. The method of manufacturing a semiconductor device, according toclaim 14, wherein the halogen element is fluorine or chlorine.
 16. Themethod of manufacturing a semiconductor device, according to claim 14,wherein the semiconductor layer is an amorphous silicon film formed by aplasma CVD method.
 17. The method of manufacturing a semiconductordevice, according to claim 14, wherein the buffer layer is an insulatinglayer formed by a plasma CVD method.
 18. The method of manufacturing asemiconductor device, according to claim 14 wherein concentration of thehalogen element in the semiconductor layer near the interface betweenthe semiconductor layer and the buffer layer is higher thanconcentration of the halogen element in the semiconductor layer near theinterface between the semiconductor layer and the substrate.
 19. Themethod of manufacturing a semiconductor device, according to claim 14,wherein concentration of the halogen element contained in thesemiconductor layer is equal to or higher than 1×10¹⁷ cm⁻³ equal to orlower than 2×10²⁰ cm⁻³.
 20. The method of manufacturing a semiconductordevice, according to claim 14, wherein the substrate having aninsulating surface is a glass substrate.
 21. A method of manufacturing asemiconductor device, comprising: forming a semiconductor layercontaining a halogen element over a substrate having an insulatingsurface; forming a buffer layer over the semiconductor layer; forming atleast one of a semiconductor element and a light-emitting element overthe buffer layer; and performing detachment inside the semiconductorlayer.
 22. The method of manufacturing a semiconductor device, accordingto claim 21, wherein the halogen element is fluorine or chlorine. 23.The method of manufacturing a semiconductor device, according to claim21, wherein the semiconductor layer is an amorphous silicon film formedby a plasma CVD method.
 24. The method of manufacturing a semiconductordevice, according to claim 21, wherein the buffer layer is an insulatinglayer formed by a plasma CVD method.
 25. The method of manufacturing asemiconductor device, according to claim 21, wherein concentration ofthe halogen element contained in the semiconductor layer is equal to orhigher than 1×10¹⁷ cm⁻³ equal to or lower than 2×10²⁰ cm³.
 26. Themethod of manufacturing a semiconductor device, according to claim 21,wherein the substrate having an insulating surface is a glass substrate.27. A semiconductor device comprising: a semiconductor layer containinga halogen element over a plastic substrate; and a semiconductor elementover the semiconductor layer containing the halogen element, whereinconcentration of the halogen element contained in the semiconductorlayer is equal to or higher than 1×10¹⁷ cm⁻³ and equal to or lower than2×10¹⁹ cm⁻³.
 28. The semiconductor device according to claim 27, whereinthe halogen element is fluorine or chlorine.
 29. The semiconductordevice according to claim 27, wherein the semiconductor layer is anamorphous silicon film.
 30. The semiconductor device according to claim27, wherein an adhesive layer is provided between the plastic substrateand the semiconductor layer containing the halogen element.
 31. Thesemiconductor device according to claim 27, wherein a buffer layer isfurther provided between the semiconductor layer containing the halogenelement and the semiconductor element.
 32. A semiconductor devicecomprising: a semiconductor layer containing a halogen element over aplastic substrate; and a light-emitting element over the semiconductorlayer containing the halogen element, wherein concentration of thehalogen element contained in the semiconductor layer is equal to orhigher than 1×10¹⁷ cm⁻³ and equal to or lower than 2×10¹⁹ cm⁻³.
 33. Thesemiconductor device according to claim
 32. wherein the halogen elementis fluorine or chlorine.
 34. The semiconductor device according to claim32, wherein the semiconductor layer is an amorphous silicon film. 35.The semiconductor device according to claim 32, wherein an adhesivelayer is provided between the plastic substrate and the semiconductorlayer containing the halogen element.
 36. The semiconductor deviceaccording to claim 32, wherein a buffer layer is further providedbetween the semiconductor layer containing the halogen element and thelight-emitting element.